Preparation of chlorides of higher fatty acids



Patented Apr. 25, 1939 UNITED STATES PATENT OFFICE PREPARATION OF CHLORIDES OF HIGHER FATTY ACIDS No Drawing. Application June 21, 1938, Serial No. 214,943. In Germany July 31, 1936 5 Claims.

My present invention relates to the manufacture of chlorides of higher fatty acids.

For the production of higher fatty chlorides, a process is known which consists in reacting higher fatty acids with phosphorus chlorides or thionyl chloride in the presence of indifferent solvents. This process yields a solution of the fatty acid chlorides which has to be worked up in order to isolate the chlorides and to recover the solvents. Fatty acid chlorides have also been prepared by reacting fatty acids with phosgene. However, when reacting higher fatty acids, it was impossible to obtain complete conversion into the chlorides and, moreover, the resulting products were darkly colored, even if alkali earth metal compounds were present as catalysts.

It is an object of my invention to furnish a method of preparing higher fatty acid chlorides which will obviate the use of solvents and which will in a very simple way allow to obtain the pure chlorides directly in practically 100% yield; especially, my invention is to be applied to the production of chlorides of those fatty acids which cannot be distilled at ordinary pressure without decomposition like, for instance, lauric acid, palmitic acid, stearic acid, oleic acid, etc.

With these and other objects in view which will be more fully apparent from the following description, my invention consists in heating a higher fatty acid in the liquid state with phosgene in the presence of and in contact with charcoal. Thereby, the higher fatty acid is practically completely converted into the corresponding fatty acid chloride, which may be separated from the charcoal by simple filtration. The fatty acid chlorides thus obtained are very pure and of clear light color. Moreover, it has been observed, that the velocity of the reaction is considerably increased by the presence of the charcoal.

The process of my invention may be carried out discontinuously or continuously. The reaction temperature can be varied within certain limits but should not be so high as to give rise to decomposition of the products, temperatures of from about 100 to about 250 being preferred. The best results so far have been obtained with activated charcoal, i. e. charcoal which has been subjected to an activating treatment with, for instance, zinc chloride, phosphoric acid, steam or the like. Other catalysts, for instance, alkaline earth metal compounds, may also be present.

The following examples serve to more fully illustrate my invention, without restricting it thereto, the parts being by weight.

Example 1 142 parts stearic acid are treated with phosgene at about 150 C., while stirring, in the presence of 1.5 parts finely pulverized activated charcoal. When no more hydrochloric acid is evolved, the resulting product is filtrated from the coal. Clear white stearic acid chloride is obtained in practically 100% yield. When working in the absence of activated charcoal, but otherwise under the same conditions, the fatty acid is converted only to an extent of about and the resulting product is of dark brown color.

Example 2 147 parts oleic acid and 3 parts charcoal having been activated in known manner with zinc chloride are reacted with phosgene at about 150 C. while stirring. When the reaction is complete the product is filtered from the coal. About 99.5% of clear oleic acid chloride being of similar color as the starting material is obtained. When omitting the activated charcoal, a darkly colored product containing only 90% of the fatty acid chloride is obtained.

I claim:

1. Process for the manufacture of chlorides of higher fatty acids which comprises heating a liquid higher fatty acid with phosgene in the presence of and in contact with charcoal at a temperature between about and about 250 C.

2. Process for the manufacture of chlorides of higher fatty acids which comprises heating a liquid higher fatty acid with phosgene in the presence of and in contact with activated charcoal at a temperature between about 100 and about 250 C.

3. Process for the manufacture of stearic acid chloride which comprises heating stearic acid with phosgene in the presence of and in contact with activated charcoal at a temperature between about 100 and about 250 C'.

4. Process for the manufacture of palmitic acid chloride which comprises heating palmitic acid with phosgene in the presence of and in contact with activated charcoal at a temperature between about 100 and about 250 C.

5. Process for the manufacture of oleic acid chloride which comprises heating oleic acid with phosgene in the presence of and in contact with activated charcoal at a temperature between about 100 and about 250 C.

ALFRED DIERICHS. 

